Compressor



June 20, 1961 1 R 0|5HE| ETAL 2,988,890

COMPRESSOR Filed July 5, 1956 5 Sheets-Sheet 1 (L /va I7 IIE/l mxfll O O nzmy a?? O Q 39 E @m ,2 Ofzzffz@ O O O A123 O O MART/N /rzea F194 @ya ATTORNEYS J. R. OISHEI ETAL June 2o, 1961 COMPRESSOR 5 Sheets-Sheet 2 Filed July 5, 1956 IIIE IN VEN TORS JOHN l2. o/sHe/ 4N@ MARTI/v /rzez BY A Tra/NE ys June 20, 1961 J. R. olsHEl E1-Al.l 2,988,890

- COMPRESSOR Filed July 5, 1956. 5 Sheets-Sheet 3 b; e4 5.4 12 INVENTORS JOHN ROISHE/ AND MART/N s/rzfz 62 36 5| 6l ATTORNEYS June 20, 1961 Filed July 5, 1956 J. R. OlSHEl ET AL COMPRESSOR 5 Sheets-Sheet 4 June 20, 1961 J. R. olsHEl ET AL 2,988,890

COMPRESSOR Filed July 5, 1956 5 Sheets-Sheet 5 pgn/5,2 .srEE/Q/A/r.; Asse/VBL y (D "0 5 (aMPzL-'sso/Q COMPEESSED A/E .e555 e ufo/Z INI/EN TOR. JOHN R. O/SHE/ AND BY MARTIN B/T'ZEE E?! (Bod/M'M/vb- ATTORNEYS United States PatentQmce 2,988,890 Patented June 20, 1961 John. R., Oula Burials and Mal-1in Bitzer, Kenmore N.Y., assignors to Trico Products Corporation, Buffalo,

' p 'Filed July s`1"9s6-,`ser.No.s96,o93

5 (Cl. 60H97) This invention relates to' compressors, and more particularly to an air .compressor poweredby pressurized lhydraulic medium for use -in a motor vehicle. i'

The motor vehicle lof today `is becoming more dependent upon power driven units, or accessories, for the operation, or' remote fcontrol, of various assemblies incorporated in the vehicle, such as a power steering arrangement, and also'suchaccessorie's as power operated windshield wiper motors, windows, folding tops, and seat positioners, kto mention but a few. The power system for operating such units may `be electrical, hydraulic, or pneumatic.

In those vehicles having a power steering arrangement utilizing pressurized hydraulic medium as a power source, a pump means for the pressurizationof such hydraulic medium 'may .be arranged for power take-off from the engine, for example, by way of the fan belt. The power Vsteering arrangement in such ya system may ybe designed 2 hydraulic medium when such medium is not required by a' power steering arrangement in the vehicle.

A `furtherobject of the invention is to provide an air compressor in a motor -vehicle which utilizes a source of pressurized hydraulic medium for air compressor operation when such medium is not being utilized by another unit in the vehicle, said system being further arranged for to supply torque for vehicle steering` 'only under certain conditions, such as where a torque of a predetermined amount has been Lapplied to the Steering wheel of the vehicle. Such power steering arrangement automatically circulates the pressurized hydraulic medium therethrough without development of turning torque when the afore- I v mentioned conditions `are not present, that is, when torque development by the `nrledium for steering fis uncalled for during rno'tor vehicle operation.

The present-invention serves as a means for development of a source of compressed air to be 'used in the, operation of certain air powered units in aV-motor vehicle. A compressor, representative of anembodiment of the invention, is so arranged in a circuitj for utilizationV of a source of pressurized hydraulic medium' for thecompression of air, when such hydraulic source is not being utilized by the power steering arrangementwof the vehicle.- To put it -another way, the compressor ofthe invention is arranged in a circuit for utilization of pressurized hydraulicmedium during those periods when such .medium is notv being called forA by the power steering arrangement for development of turning torque. The pressurized hydraulic medium, instead of circulating freely through the power steering arrangement without development of turning torque, may be automatically diverted to the compressor for compression of air, which is directed to` a storage tank t'o be drawn off by the various air operated units as required. f v

The main object of this invention is to provide an air compressor forise in a motor vehicle, which compressor is powered by pressurized hydraulic medium.

Another bjeet'orth invention is te provide a cempr'esso' for use in a motor vehicle which utilizes a Ascmrce of pr suri'zed hydraulic medium Ywhen such medium is not being vcalled for by another unit, or accessory, of ithe motor yehic'le; p

A further object of the invention` is 'to provide a system including the deviee ofthe invention, 'iii` which va source of pressurized 'h raulic is utilizedjfor operation of multiple um in' the .motor Vehicle' but with certain of .these units gi've a preference over others in ntte'r et jet efth invention isv te provide a ys'tem in a nifot'r' vehicle, pvvhili syste includes a hy Aally powered air compressor arranged to 'pressm7d"""" termination of compressor operation when air has been compressed in a storage tank to a predetermined degree whereupon the medium -is redirected to the other unit.

These and further objects and features of the invention will become more apparent from the following description and the accompanying drawings wherein:

FIG.- l is a fragmentary perspective view of a motor vehicle illustrating the device of the invention applied to the vehicle;

FIG. 2. is a top plan view of -a pilotvalve block used in the device of the invention;

FIG. 3 is aside View of same;V FIG. 4 is a bottom plan view of same; Y Y FIG. ,5 is a section View as seen from line V-V in FIG- Z;

FIG. 6 is a plan view of the device of the invention; FIG. 7 is a section view as seen from line VII-VII in FIG. 6;

Y FIG. 8 is a view as seen from line VIII--VIII in FIG- 7.;

FIG. 9 is a view as seen from line IX-IX in FIG. 7; FIG. l0 is a section view of a solenoid operated valve `mechanism used in connection with the device of the inventions,

FIGS. 11, 12, 13 and @14 are schematic representations lof the device of the invention illustrating the relative tied manner in which the compressor of the invention may be connected -to complementary units included in the system of the invention. Y N,

YReferring to the drawings, and morevparticularly to FIG.` 1 numeral 16 identities a motor vehicle having engine 17, fand a'battery 18 installed therein in the usual manner; and a steering mechanism 19, including a power steering assembly 217 having a distributing valve 2,0 which automatically directs hydraulic fluid flow for development of turning torque under certain conditions ofvehicle steering, as is well known to those skilled in the A hydraulic pump unit A22, arranged for power takeoff from an engine as illustrated by use of amfan belt 23, is adapted for the pressurization and circulation of hydraulic iluid, such as oil, to the lpower steering `assembly Z1. The latter is so arranged as to utilize the pressurized hydraulic fluid for generation of torque as required by the steering mechanism for power steering, and is further arranged for the by-passing of the pressu'rized hydraulic lluid when torque is not required by the steering mechanism, A circuit for conduction of hydraulic fluid between the pump unit 2.2 and the power steering assembly 21, includes certain conduits, or hoses, as will be identified later herein.

Positioned within the motor vehicle is a compressed air storage tank, or reservoir, 25 which serves as a source of compressed supply for pressure operated units, such as a fluid pressure operated wiper motor 24, connected to the reservoir by a conduit, or hose 26. A solenoidoperated hydraulic valve assembly 27 is interposed in the hydraulic circuit leading from the pump units 22 to the power steering assemblyI Z1. A hydraulically operated compressor 28, representing an embodiment of the invention, is connected to the steering assembly 21 and fthe reservoir 25, by conduit, Aor hose means, in ai mannerf which will be described in detail hereinafter.

As bes-t seen in FIGS. Z-9, the compressor 28 includes a hydraulic portion 29 and a pneumatic portion 31, said portions being joined by fastening means, such as screws 32. A compound piston assembly 33 is adapted for reciprocating motion in said portions, and more specifically has piston heads -34 for reciprocating movement solely in ja piston chamber 30 formed in the hydraulic portion 29, and a piston head 36 arranged for reciprocating motion solely within a piston chamber 35 formed in the pneumatic portion 31. The piston heads 34 are adapted -for Areciprocating movement as a result of hydraulic pressure being alternately applied thereagainst, which movement `is transmitted to the piston head 36 for compression of `air in the pneumatic portion.

The hydraulic portion includes a cylinder housing 37, having an integral ange 38 at one end for connection with the pneumatic portion 31, a valve block 39, and a "valve housing 41. The valve block 39 is arran-ged between the valve housing 41 and a valve head portion 42 formed on the cylinder housing 37. The piston heads 34 are ar- -ranged to divide the piston chamber 30 into three volumes 43, 44 and 46, volume 43 being of xed size, while volumes `44 and 46 are of variable size depending upon the position of the piston assembly 33 within the piston cham- 4'ber 30. A piston valve head 47 is aflxed to thepend of the piston chamber 30 by fastening means such as lscrews 48.

The pneumatic portion 31 includes a cylinder 49 alhxed to the flange 38 by the screws 32, and a cylinder head 51 which is affixed to the cylinder by fastening means such as screws 52. Air intake passageway 53 formed in the cylinder 49 extends between a poppet valve `54, arranged in the flange 38, and a poppet valve 56 arranged in the -cylinder head 51. Diametrically opposite passageway 53 v is an air exhaust passageway 57, which extends between a chamber 58, containing a poppet valve 59, and a chamber 61, containing a poppet valve 62. Each of the poppet valves has a compression spring to urge the poppet valve ltoward cylinder 49 for regulation of air flow into and out of the piston chamber 35, as will be explained in furyther detail. A threaded recess 63 is arranged for reception of a. conduit, or hose, 64 connecting the air intake passageway 53 with an air strainer 66, while a threaded recess 67 is arranged for reception of a conduit, or hose 68 ,the other end of which connects with the reservoir 25.

The Valve housing 41 has a cylindrical chamber 69, with the longitudinal axis thereof arranged parallel to that of lthe piston chamber 30, in which is arranged for recipro "cable motion a reversal, or spool valve, 71. ,valve has -four pistons 72, 73, 74 and 76 arrangedvtoprovide volumes 77, 78, 79, 81 and 82; volumes 78, 79, and

-81 are of fixed size, whereas, volumes 77 `and 82 are of variable size depending upon the position of the spool valve 71 in the chamber 69. At each end of the chamber 69 is a threaded plug 83 for closing the ends of said chamber. A boss 84, projecting from the exterior top surface of the valve housing 41, has a threaded opening 86 for reception of a conduit, or hose, 87 the other end of which is affixed to the hydraulic valve assembly 27. Extending from the threaded opening 86 is a passageway 88 which vopens into the mid-point of the chamber 69. It is to be noted that the spool valve 71 has end projections 89 for abutment with an adjacent threaded plug 83, to thus x Vthe minimum size of volumes 77 and 82.

The valve block 39 has a cylindrical chamber 91, with the longitudinal axis thereof perpendicular to that of the cylindrical chamber 69, and a pilot valve 92, reciprocably arranged within chamber 91. Threadably aixed at each end of the chamber 91 is a threaded plug 93. The pilot valve has pistons 94, 96, 97 and 98 which are arranged to provide volumes 99, 101, '102, 103, and 104 in the charnber 91, volumes 101, 102 and 103 being of fixed size, while volumes 91 and 104 are of variable size depending upon the position of the pilot valve within the chamber.

A-At each end of the pilot valve are projections 106, fOr

The spool abutment with an adjacent threaded plug 93, to thus establish the minimum size of volumes 99 and '104.

A plurality of passageways, arranged between the various units comprising the hydraulic portion, are best described with reference to FIG. 1l. Passageways 107 and 108, opening into the chamber 69 in the region of volumes 78 and 81 respectively, extend from the housing 41, through the valve block 39 and into a horizontal passageway 109, formed in valve head portion 42; a vertical passageway 111 connects with passageway l109 and opens into the piston chamber 30 at the mid-portion thereof. Passageways 112, 113 and 114, open into the chamber 69 in the region of the mid-portion thereof. Passageway 1112 extends through the valve block 39 and leads to yand opens into one end of the piston chamber 30, in the region of volume 46; passageway 114 extends through the valve block 39 and leads to and opens into the other end of the piston chamber 30, in the region of volume 44; and passageway 113 leads to and opens into the mid-portion of the cylindrical chamber 91. It will be seen that when the spool valve 71 is in extreme left position (FIGS. 7 and .'11) in the chamber 69, passageways 88, 1,12, and 113 will be in communication with volume 79, while passageways .114 and 108 will be in communication with -volume 81, `and passageway 107 will be in communication with volume 78.` When the spool valve 71 is positioned at the yopposite end of the chamber 69, as in FIG. 12, passageways 113, 114 and 88 will be in communication with volfume79, passageways 112 and 107 will be in communica-y tion with volume 78, and passageway 108 will be in communication with volume 81.

Passageway 116 opens into the end of chamber 69 in the region of volume 77, and its other end leads to and opens into a mid-portion of the chamber 91; passageway 117 opens into the opposite end of the chamber 69 in the regionof volume 82, and leads to and opens into the mid- -portion of the chamber 91. Passageways 118 and 119, opening into the chamber 91 in the region of volumes 101 and 103 respectively, are connected to a passageway 121 which is in communication with horizontal passageywayy 109. 'Passageways 122 and 123, opening into' the chamber 91 in the region of volumes 104 and 99 respectively, lead to and open into the piston chamber 30 in the nud-portion thereof. 4

' It will be seen that when the pilot valve is positioned toward the right endfof the chamber 91 (FIG. 1l), passageways-113 and 117 will be in communication with volume 102, lpassageways 116 and 118 will be in comlmunication with volume 101, and passageway 119 will be in communication with volume 103, when the spool 'valve is positioned at the opposite end of the chamber 91, (FIG. l2) passageways 113 and 116 will be in communication with volume 102, while passageways 117 yand I119 will be in communication with volume 103, and passageway 118 will be in communication with volume 101. A threaded recess 124, arranged for reception of a conduit, or hose, 126 is located at the mid-portion of the piston 'chamber 30 to connect volume 43 with a conduit, or hose, 1'127 arranged `for return flow of hydraulic medium to the pump unit 22.

vReferring to FIGS. 1 and 10, the hydraulic valve as- ,sembly 27 includes a threaded recess 128 for reception of a` conduit, or hose, 1429 connected to the pump unit .22, a threaded recess 131 for reception of the hose 87 connected to the compressor 28, and a threaded recess 132 for reception of la hose 133 leading to the power steering assembly 21. The valve assembly 27 has a solevnoid 134 arranged for the shifting of a spool valve 136,

-the, solenoid 134 is inactivated, so that connection is made between conduits 129 and 87 for flow of hydraulic fluid from the pump uni-t 22 to the compressor 28.

assenso solenoid cont-rolledvalve 1,38, connected to lignition switch 1'39`is located in theconduit- 26 extending between the reservoir` 25 and the wiper motor 24. The valve V138 permits `thepneumaitic circuitV between the reservoir and wiper motor to be opened when the ignition is turned on; spring means (not illustrated) arranged inthe valve 138 closes the valve when the' ignition isV turned olf, so, that leakage of airfrom the reservoir through the wipermotor is prevented when the vehiclehis not in operation;

AV pressure operated electr-ical switch 141 is mounted upon the reservoir 25 whichY switch is responsive to a predetermined pressure in the reservoir 4to activate the solenoid 134 of the valve` assembly 27,/ to thus discontinue operation of the compressor 28,k hy diverting hydraulic iluid to the steering assembly 21, when the pressure in the reservoir attains said` predetermined amount. A switch means 142, is responsive to movement of theV distributing Valve 20, to ,complete the circuit through the solenoid 134 of vthe valve assembly 27, and thus direct hydraulic uid to the steering assembly 21, yfor development of turning torque. 1 Y Y 'I'he operation of the compressor 28 will now be Vdescribed. Y

Referring to FIG. l1, the position of the movableparts of the compressor are shown during operation, with the piston assembly 33 moving in the direction of the 'cylinder 'h'ead 51. For purposes of clarification, arrows have been used in the illustration to indicate the type and direction of iluid flow in the passages and chambers, viz., single-headed arrows indicate air ow underatmospheric pressure, double-headed arrows indicate pressurized air ilow, and triple-headed arrows indicate ow of pressurized hydraulic medium, such as oil, coming from the pump unit 22 via valve assembly 27.

, Pressurizedl hydraulic medium entering the compressor through hose 87, passes through the passageway 88` into volume 79 of the spool valve 71, and into' passageway 11-2 to piston volume 46, to exert a force yupon the piston assembly 33, thereby causing motion of piston head 36, resulting in compression of air in piston chamber 35, which flows from thepiston chamber, past poppet valve 62 into air exhaust passageway 57, and hose 68. As the piston head 36 is moving withinv the piston chamber 35, the poppet valve 54 will be unseated vtoiallow flow of air under atmospheric pressure into the piston chamber on the side of the piston head opposite to which compression is taking place. The pressure of hydraulic fluid in volume 79 is transmitted through passageway 113, volume 102 of the pilot valve 92, through passageway 117, into'van'iable volume 8:2, to act against piston 76 of the spool valve 71, while simultaneously the variable volume 77 is open to the' exhaust 127 leading to the inlet of pump 22 via passageway 116, volume 101, passageway 118, passageways 1221, 109, 111, and piston volume 43. The pressure diierential thus established upon the spool valve 71 is effective to maintain the latter in the position illustrated.

When the piston assembly 33 has neared the end of its movement, as above described, the end of passageway 122 will be uncovered by a piston head 34, resulting in `'the connection of passageway 122 to volume 46, as illustrated in FIG. l2. Immediately upon such action, pressurized hydraulic medium will ow from passageway 122 into variable volume 1'04 of lthe pilot valve 92, to exrt a pressure upon piston 98, resulting in the shifting ot the pilot valve to the other end of the chamber 91, as illustrated in FIG'. l2. Variable volume 99, being connected to the exhaust hose 127 via passageway 123, and piston volume 43, results in the establishment of a pressure differential between the ends of the pilot valve, resulting in the movement thereof. As soon las such movement of the pilot valve occurs, hydraulic flow in passageway 113 will `be directed to passageway 116 via volume `1042, to the variable volume 77 resulting in pressure against the pistonl 72. Simultaneously, .the hydraulic iluid in varia- :ble volume 82 will be released to the exhaust hose 127 via passageway 117, volnme 103, passageways 119,121, 10i/l, and 111,1, through piswnV ,volume 43- AS e roultvf, pressure diteren/tial thus establishedv on the spool lvalve 71, movement of the spool valve will take place toward the opposite end of therchamber 69f In such position of the spool valve, it'will be seen that pressurized hydraulic fluid will pas's from the volume 79 into passageway 114', and into` variable piston volume 44 to ac t against piston headV 34, and atv-,the same time piston volume 46 will be opento the exhaust hose 127 via passageway 112i, volume A7,8, passageways 107, 109 and 111",u and through pistonyk volume 43; As a result, movement of the piston assembly 33 willpcommence in a reverse direction as illustrated' in FIG.A 1 3. y y l, Y l,

Such movement otpthe piston assembly 33 will result in the compression of vair in the piston chamber 35 between the piston head 36 and the flange 38', resulting in the unseating of poppet Valve 59 and the ow of` comL Vpressed air into chamber 58 and exhaust air passageway 57 to the hose 68,. During such movement of the piston assembly, air under atmospheric pressure will ow in the passageway 53, past poppet vvalve 56, and into the piston chamber 35 `on the side of the piston head opposite to that onfwhich compression of airis taking place.

AMovement ot the piston assembly in such direction will continue until a piston head 34 uncovers the end of passageway y123. When this occurs, pressurized hydraulic medium will flow through passageway 123, into volume 99 of the chamber 91 to exert pressure against the piston 94. At the same time, the variable volume 104 will be connected to the exhaust hose 127 via passageway 122, and piston volume 43, thus resulting in movement of the pilot valve to 'the opposite end of the valve chamber 91, as illustrated in FIG. 14. [In such position, the pilot Valve will establish connection of the passageway 113 with passageway 117 via volume 10l2, resulting in hydraulic uid flowA into variable volume 82 of the spool valve 71.v At the same time, variable volume 77 will be connected with the exhaust hose 127 vial passageway 116, volume 101, passageways L18, 121, 109, and 111, through piston volume 43. The spool valve 71, as a result of pressure difvferential established between pistons 76 and 72, will be shifted to the other end of the chamber 69.- In this position of the spool valve, hydraulic pressure' fluid will 110W from volume 79 into passageway 112, and thenc'e into piston ,volume 46 to act against piston head 34, while at the same time, yariable volume 44 will be connected to exhaust hose 127 via passageway 114, volume 81,- and passageways 108, 109, 111, and volume 43. As a result of the pressure differential acting upon the piston heads 34, movement of the pis-ton assembly will commence in the opposite direction, to .thus cause compression' of air in the piston chamber 35, between piston head 36 and cylinder head 51.

It may be stated that the poppet valves are each spring lloaded to permit unseating of each poppet valve in a predetermined manner. More particularly, the spring of poppet valves 54 and 56 are of such strength as to allow uns-eating of the valve under the pressure differential established between the exterior atmospheric vpressure and the interior sub-atmospheric pressure existing in the cylinder, while the springs of poppet valves 5'9 and 62 are adapted for unseating lof the puppet valves when the pressure diierential between the air within the cylinder and the air inthe volumes of chamber 58, passageway 57, and hose 68 has risen to a predetermined amount.

rIhe circuit arrangement illustrated in FIG. 15, diifers from the circuit arrangement described above primarily in the use of a hydraulically pressure operated valve 146 in place of the hydraulic valve assembly 27 which is a solenoid controlled type of valve. For simplification,

the following description, the elements identical with those described above, have been given the same numerals.l VA second valve 147 is arranged for connection to the distributing valve 20 in such a manner that movement of the distributing valve 20 will Acause movement of a piston 148 slidably arranged in the valve 147. As shown in FIG. 15, the piston 148 of valve 147 is in a neutral or non-operativeposition, which occurs when the power-steering assembly 21 is not utilizing oil for development of turning torque. It will be seen that in such position of the piston 148, oil from the pump 22, flowing in a hose 149, will enter the valve 146 between piston heads 151 of a piston 152, from whence it will ow into a hose 153 connected to 'the compressor 128 for operation of the compressor. At'the same time, oil will enter the hose 154 which is 'connected to the movable portion of the valve 147, said oil ow in hose 154 entering the valve between piston heads `156 of the piston 148, such flow ending when the volume between piston heads 151 is completely iilled by the oil.

When oil is required for development of turning torque in the power-steering assembly 21, the distributing valve 20 will shift, resulting in movement of the piston 148 toward one or the other end of the valve 147, depending upon the direction of vehicle steering. Such movement of the piston 148 will cause oil flow from hose 154 into the volume deiined by the piston heads 156, and then into hose 157. The hose 157 is connected a-t the other end to the lower part of the valve 146 in a region below the bottom piston head 151, whereby oil flow from hose 157 will lcause upward movement of the piston 152. As a result thereof, oil flow from hose 149 will be shut oif from hose 153 and instead will be directed into hose 158, the opposite end of which connects with the distributing valve 20. Such oil flow into the distributing valve 20 will be directed into pipe 159 or 161, for development of turning torque in the power-steering assembly for turning in a right or left direction accordingly. Upon completion of the vehicle turning operation, that is, when pressurized oil is no longer required for development of turning torque, the distributing valve 20 will move so that the piston 148 will be returned to its neutral position (FIG. v15). It will be seen that when the piston 148 returns to neutral position, the oil entrapped under the lower piston head 151 may ow through hose 157 into the valve 148, through a volume defined by one of the piston heads 156 and a piston head 162 into a hose 163 which joins with a hose 164 provided for the return ow of oil from the distributing valve 20 back to the oil pump 22. Movement ofthe piston 152 downwardly is etected by a helical spring 166 arranged at the top end of the piston 152, which spring is compressed during upward movement of the piston.

A hose 1.67 connects ythe compressor 28 to the reservoir 25, while a hose 168 connects the reservoir to the lower end of the valve 146. A release valve 169 is adapted to allow flow of compressed air into the hose 168 when pressure in the reservoir attains a predetermined value, said release valve being further arranged for venting of the hose 168 to atmosphere when the release valve is in closed position. It will be seen that compressed air flowing from hose 168 into the valve 146, will act upon a piston 171 to move the latter upwardly into abutment with the piston 152, `to cause movement of the piston 152 upwardly, so that oil ow in hose 149 will be continued in hose 158, while flow of oil into the hose 153 will be cut oi. In such manner, operation of the compressor 28 will stop when compressed air pressure in the reservoir attains a pedetermined value. Oil ow thus directed into hose 158, passes through .the distributing valve 20 and into hose 164, such oil flow continuing until the distributing valve 20 is fixed for directing of oil into pipes 158 or 161 for development of turning torque, or until pressure in reservoir 25 drops below -the predetermined value as determined by the setting of the release valve 169. When air pressure in the reservoir drops below the predetermined value, the release valve 169 will be closed, hose 168will be vented to atmosphere, piston 171 and 152 will-be moved downwardly inthe valve b-y action of spring v8 166, and oil tlow will again occur from hose 149 into hose 153 to cause operation of the compressor 128.

From an understanding of the foregoing, it will be seen that the compressor of the invention may be connectedv to the oil pump 22 and the power-steering assembly 21 for operation regulated by a hydraulically pressure operated valve 146, the action of which is controlled by a valve 147 responsive to movement of the distributing valve 20 of the power-steering assembly 21.

The foregoing description has been given in detail for clearness and without thought of limitation sincethe inventive principles involved are capable of assuming other physical embodiments without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is: l

1. In a motor vehicle, Ithe combination including a power-steering arrangement utilizing pressurized hydraulic medium for development of turning torque under certain conditions of vehicle steering, an -air compressor having operating means powered by the pressurized hydraulic medium, a reservoir coupled to the compressor for the storage of compressed air, a valve means for directing pressurized hydraulic medium alternatively to the powersteering arrangement and to the operating means of the air compressor, said valve means when in non-operative position directing said medium to the operating means of said air compressor and when in operative position directing said medium to the power-steering arrangement, switch means actuated by the power-steering arrangement for `establishing said operative position of said valve means, and a pressure responsive means establishing said operative position of the valve means when air pressure in the reservoir rises -to a predetermined value.

2. In a motor vehicle having a source of pressurized hydraulic medium, the combination including a powersteering arrangement having control means directing hydraulic medium within the power-steering arrangement for development of turning torque under predetermined conditions of vehicle steering, said control means allowing the bypass of pressurized medium in the absence of said conditions of vehicle steering, an air compressor hav ing operating means powered by pressurized medium, a reservoir coupled to the compressor for the storage of compressed air, a valve having an operative position for direction of pressurized medium to the power-steering arrangement, said valve having a non-operative position in which pressurized medium is directed to the operating means of said air compressor, and pressure operated means establishing said operative position of said valve means when air pressure in the reservoir rises to a predetermined value.

3. In a motor vehicle, the combination including a power-steering arrangement utilizing pressurized hydraulic medium for development of turning torque under certain conditions of vehicle steering, an air compressor having operating means powered by pressurized hydraulic medium, a reservoir coupled to the compressor for the storage of compressed air, a solenoid operated valve alternatively directing pressurized hydraulic medium to the power steering arrangement and to the operating means of said air compressor, said valve having a non-operative position directing said medium to the operating means of said air compressor and an operative position in response to switch means associated with the power steering arrangement directing said medium to the power steering arrangement, and a pressure operated switch means on the reservoir energizing the solenoid valve for movement to operative position when air pressure in the reservoir rises to a predetermined value.

4. In a motor vehicle, the combination including a power-steering arrangement utilizing pressurized hydraulic medium `for development of turning torque under certain conditions of vehicle steering, an air compressor having operating means poweredy by pressurized hydraulic medium, a reservoir coupled to the compressor for the storage of compressed air, a first valve means having a piston normally positioned for directing pressurized hydrauli'c medium to the operating means of said compressor, said piston being movable for direction of pressurized hydraulic medium to the power-steering arrangement, a second valve means responsive to the power-steering arrangement and having a piston movable to direct pressurized medium for movement of the piston in the first valve means, said second valve piston being movable during utilization of pressurized hydraulic medium by the power-steering arrangement, and means including a conduit between said reservoir and the iirst valve means for movement of said rst valve piston when the compressed air pressure in the reservoir attains Ia predetermined value.

5. In a motor vehicle, the combination including a power-steering arrangement utilizing pressurized hydraulic medium for development of turning torque under certain conditions of vehicle steering, van air compressor having operating means powered by pressurized hydraulic medium, a reservoir coupled =to the compressor for the storage of compressed air, a valve means for selectively directing pressurized hydraulic medium to one of the power-steering arrangement and the operating means of said -air compressor, said valve means when in one position directing said medium to the operating means of said air compressor and when in another position directing said medium to the power steering arrangement, switch means responsive to the power steering arrangement to hold the valve means in said other position, and a pressure responsive means establishing said other position of the valve means when air pressure in the reservoir rises to `a predetermined value.

References Cited in the iile of this patent UNITED STATES PATENTS 1,923,333 Soter Aug. 22, 1933 2,209,090 Pierotti et al. July 23, 1940 2,331,108 De Ganahl Oct. 5, 1943 2,363,179 Harrington et al Nov. 21, 1944 2,462,983 MacDuiT et a1. Mar. 1, 1949 2,624,361 Brown Jan. 6, 1953 2,674,092 Gardiner Apr. 6, 1954 2,737,196 Eames Mar. 6, 1956 

